Capacitive Sensing Systems Analysis for Oil Quality Monitoring of Hydraulic Systems

Hydraulic oils are essential for properly functioning industrial machinery and engines in the automotive and aerospace sectors. However, the quality of these oils can be compromised by contamination, which adversely affects their chemical and physical properties, linked to the oil's dielectric characteristics, which can be diagnosed using appropriate sensors. To this end, three different capacitive sensor architectures, each with different geometries and characteristics, are proposed and analysed in this work. Due to the complexities involved in simulating the dielectric properties of fluid mixtures, an entirely experimental approach was adopted to ensure consistency with real-world scenarios. Analyses were conducted at different concentrations of two types of typical pollutants: water and diesel. Preliminary results highlight the good performance of the proposed architectures in terms of sensitivity and selectivity, as well as the importance of proper detection system design to ensure efficient oil quality monitoring and diagnosis in different critical applications.